1. Field of the Invention
The present invention relates to a photo film cassette for a lens-fitted photo film unit and a method of marking a photo film cassette. More particularly, the present invention relates to a film cassette provided with indicia convenient for use with various types of lens-fitted photo film unit.
2. Description Related to the Prior Art
There is a known lens-fitted photo film unit sold under a trade name of "Fujicolor Quick Snap" (manufactured by Fuji Photo Film Co., Ltd.), in which a film housing is pre-loaded with unexposed 135 photo film and provided with a simple mechanism for photography. To mount the photo film in the lens-fitted film unit, a film cassette of a widely used 135 type is incorporated in association with it. During assembly of the lens-fitted photo film unit, the photo film, pre-contained in the cassette, is pulled out of the cassette and formed in a shape of a roll. The cassette is inserted in a cassette containing chamber at the same time as the roll of the film is inserted in a film supply chamber.
When the film is wound for use of the lens-fitted photo film unit, a spool inside the cassette is rotated to wind the film after exposure into the cassette. When the film is fully exposed, the whole of the lens-fitted photo film unit is forwarded to a photo laboratory via a photofinishing agent. In the photo laboratory, the cassette with the exposed film is removed from the film housing. The film is developed, and subjected to printing to obtain photo prints. The photofinisher returns the film to the customer, and provides him with the prints.
In the film cassette, a spool is contained rotatably and has a roll of photo film wound on the spool. A cassette shell consists of a metal tube formed from a piece of plate and a pair of caps fitted on respective ends of the tube. A surface of the tube is provided with printed decorative patterns and letters including: the manufacturer's name, the maximum photographable number of exposures on the film, a trade name of the product, and film sensitivity according to the International Organization of Standard (ISO). Those are printed on the tube by means of printing plates, whether the cassette is to be sold independently or used in a photo film unit.
However, the printing operation by use of printing plates requires the preparation of plates, pretreatment wherein plate surfaces are coated with a white ground layer consisting of a specialized solvent, a post-treatment wherein portions printed with ink are dried by a dryer. Those steps result in a high cost for the printing although they can record printed images in high quality.
Nowadays there are plural variants of lens-fitted photo film units for purposes of photography in various manners. A model known as "Fujicolor Quick Snap +3" (trade name; manufactured by Fuji Photo Film Co., Ltd.) is capable of effecting 27 exposures on the film having a length standardized for 24 exposures, as the film is positioned with high precision when pre-loading the photo film unit with the film. There is another type of photo film unit in which a pair of opaque movable plates for shielding light are arranged in front of an exposure aperture and associated with a photographic light path, to change over the frame size between the 35 mm full size and a panoramic size 36.times.13 mm in which the full size is narrowed.
When the film is exposed in the panorama-changeable type, the film is provided with a mixture of full-size frames and panoramic frames. If a photofinisher does not know the mixture of the two frame sizes before the development, the development can be impeded. However the printing of indicia of the mixture information on the film cassette is disadvantageous if by use of printing plates, which must be prepared relative to each of the various types. The number of such printing plates thus required is excessively great. Lines and processes for printing on the film cassette are likely to raise expenses. Another drawback lies in low speed in the printing processes.